Background: Risperidone has been reported to
alleviate the severity of tardive dyskinesia, but without placebo
control, the possibility of spontaneous tardive dyskinesia
remission after discontinuing original conventional
antipsychotics cannot be excluded. This 12-week randomized,
double-blind, placebo-controlled study investigated the effect of
risperidone on severe tardive dyskinesia.

Method: Forty-nine DSM-IV schizophrenia patients
with severe tardive dyskinesia were enrolled in the study. After
a 4-week washout period, the subjects were randomly assigned to
treatment with either risperidone or placebo. The risperidone
dose was started at 2 mg/day and gradually increased to 6 mg/day
over 6 weeks; the 6-mg/day dose was maintained for the remaining
6 weeks of the study. The subjects were evaluated every 2 weeks
with the Abnormal Involuntary Movement Scale (AIMS) and the
Extrapyramidal Symptom Rating Scale. The final mental status was
assessed with the Brief Psychiatric Rating Scale.

Results:Twenty-two subjects in the
risperidone group and 20 subjects in the placebo group completed
the study; the mean baseline AIMS total score for all subjects
was 15.9 ± 4.6. At the end of the study, the mean AIMS total
score decrease was 1.1 ± 4.8 in the placebo group and 5.5 ± 3.8
in the risperidone group (p < .05). Fifteen subjects (68%) in
the risperidone group and 6 subjects (30%) in the placebo group
were responders (p < .05). The risperidone responders had a
mean AIMS total score decrease of 7.5 ± 2.1. More significant
tardive dyskinesia improvement among the risperidone group was
noted from the eighth week and was mainly demonstrated in the
buccolinguomasticatory area rather than in choreoathetoid
movement of the extremities (p < .001).